The invention describes apparatus for the observation of processes, especially of processes in vacuum technology, with a viewing glass disposed behind a chamber, past which a rotating device moves to prevent contamination of the viewing glass.
It is generally known to provide a hand shutter on a viewing glass on the wall of an opaque chamber. Here the danger is that if the shutter is open too long, severe contamination of the viewing glass will occur, rendering it opaque. This opaque condition will preclude further satisfactory observation of the process.
To minimize the chance for an opaque observation glass, it is known that the observation glass can be wiped with oil before the vapor depositing process is initiated so as to protect it from being vapor-coated subsequently. This method of preventing observation glass contamination is very problematical from a technical viewpoint because the oil impairs vision through the glass and can also result in contaminating the substrate being coated in the process.
Another way to alleviate the problem is a disk stroboscope which is driven at the center by a motor. Since a motor disposed in this manner occupies a great amount of space, the disk has to be very large so that there will be enough room alongside the motor for an opening through which the process in the vacuum chamber can be observed.